1. Field of the Invention
The present invention relates to an electronic high-voltage generator for electrostatic sprayer devices comprising a charging electrode, the sprayer devices being formed of a controllable low-voltage d.c. voltage source, a frequency-clocked power amplifier for converting the d.c. voltage into an alternating voltage, and a transformer for converting the low-voltage alternating voltage into a medium high voltage alternating voltage, and a high-voltage cascade for converting the medium high voltage alternating voltage into a high-voltage d.c. voltage, and particularly for hand spray guns in which the transformer and the cascade are integrated in the gun.
2. Description of the Prior Art
Various embodiments of the type of high-voltage generator generally set forth above are commercially available, and either represent a separate element connected to the spray gun by way of a high-voltage cable or the transformer and the high-voltage cascade or multiplier are accommodated in the gun and are connected by way of a low-voltage line to the unit containing the other components of the high-voltage generator. When producing such sprayer systems, the individual electronic components are designed such, particularly an oscillator having an oscillation frequency for clocking the power amplifier, that the high-voltage generation occurs with the lowest possible power losses, in particular that the transformer functions optimally loss-free (resonant range). Despite this prematching, however, considerable power losses occur in the practical operation of such sprayer systems, particularly because the prematching is necessarily based on fixed values with respect to the connecting line between the high-voltage generator or, respectively, high-voltage generating portion and the spray gun, as well as with respect to the load. It is precisely the load, however, that is dependent on the distance between the charging electrode and the workpiece to be sprayed, the type of sprayed material and the like which is subject, in practice, to considerable changes or, respectively, fluctuations, particularly in the case of hand sprayguns. The consequence of these considerable losses is not only an inefficient operation, but also the requirement to provide for a corresponding heat dissipation, for instance at series resistors. In spray guns wherein the transformer and the high-voltage cascade are accommodated in the gun, a further disadvantage occurs in that, in order to avoid overheating damage, limits are placed on the miniaturization of these components, this leading to the fact that they are relatively large and heavy and, therefore, unwieldy, particularly in the case of hand sprayguns.